This invention relates to a D.C. power supply apparatus which prevents a feeder voltage drop in an electric railway power line adopting a D.C. feeding system.
In the electric railway power line which adopts a D.C. feeding system, rectifier substations have heretofore been installed at intervals of several kilometers to about 10 kilometers. In a high capacity substation, electric power is received at an extra-high voltage of at least 20 kV and is converted into a predetermined D.C. voltage, which is fed to an overhead line.
However, in the case where an extra-high voltage feeder does not exist near a site for installing the substation, feeding facilities for the extra-high voltage must be disposed over a long distance to the position of the substation, and the installation cost of the rectifier substation including the expenses of the feeding facilities becomes very high. On the other hand, when as a countermeasure, the rectifier substations are installed in places accessible to receiving electric power of the extra-high voltage, the intervals of the rectifier substations become very long in some cases. This leads to the problem that the D.C. overhead line voltage at an intermediate point between two adjacent substations or at an end point (remotest point from the last substation) lowers abnormally during the running of an electric vehicle or train.